Application of a Thermodynamic Consistency Test to Binary Mixtures Containing an Ionic Liquid

ABSTRACT

A thermodynamic consistency test developed for high pressure binary vapor-liquid mixtures is applied to mixtures containing a supercritical solvent and an ionic liquid. Several authors have reported vapor-liquid equilibrium data on the binary systems supercritical CO2 + 1-butyl-3-methyl imidazolium hexafluorophosphate {[bmim][PF6]}, supercritical CO2 + 1-butyl-3-methyl imidazolium nitrate {[bmim][NO3]}, supercritical CO2 + 1-butyl-3-methyl imidazolium tetrafluoroborate {[bmim][BF4]} and supercritical CHF3 + 1-butyl-3-methyl imidazolium hexafluorophosphate {[bmim][PF6]}, but some of these data differ dramatically. The Peng-Robinson equation of state, coupled with the Wong- Sandler mixing rules, has been used for modeling the vapor-liquid equilibrium of these binary mixtures. Then, the proposed thermodynamic consistency test has been applied. The results show that the consistency test can be applied with confidence, determining consistency or inconsistency of the experimental data.